Television



Sept. 25, 1956 J. E. BAMBARA 2,764,528

TELEVISION Filed March 19,. 1952 17 FIG.I Q/ 146:\14B Q 4 Sheets-Sheet lRECEIVER CIRCUIT VIDEO CHANNEL DEFLECTION CHANNEL GB RGBRG FIG. 3 f L 926 a 14/? M a ATTORN 4 Sheet-Sheet 2 J. E. BAMBARA TELEVISION 32a 1 WWAA 1 32a J 'JJ-| am: U- l I 33 I .1

RED 9 Se t. 25, 1956 Filed March 19, 1952 Sept. 25, 1956 J. E. BAMBARATELEVISION 4 Sheets-Sheet 3 Filed March 19, 1952 FIG. 8

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FlGJOcI INVENTOR (Ins-(pi if jaw/dare Unite 2,764,628 TELEVISION JosephE. Bamhara, Brooklyn, N. Y., assignor to Columbia Broadcasting System,Inc, New Yorir, N. Y., a cor poration of New York Application March 19,1952, Serial No. 277,500 27 Claims. ci. 1-7s--s.4

States Patent At the present time there have been a number ofproposalsfor tri-color cathode-ray tubes in which pictures are reproduced inthree primary colors on substantially the same area of the viewingscreen. In some tubes of this type a perforated mask is placed in thepath of the electron stream to the viewing screen and in another type apair of intermeshed Wire grids is arranged in the path of the electronstream. In the mask type of tube, three electron guns are commonlyemployed so that the three electron beams passthru a given aperture inthe mask at different angles to impinge on three separate elementalareas of the viewing screen, and the three elemental areas fiuoresce inthree primary colors, respectively. A single gun version has also beenproposed in which a deflecting field is employed to cause the electronbeam to pass thru the mask atthree different angles successively,thereby impinging on the three elemental areas of different color.

In the case of the grid type of tube, one electron gun has beensuggested and the two sets of grid Wires energized so that the electronbeam is focused and deflected to elemental screen areas of diiferentprimary color.- In this case also, a three-gun version has been proposedin which the directions of the electron beams determine which colorphosphors are energized, and the grid is employed to focus the severalbeams.

In the three-gun versions of tubes of this general type, a problem ofregistering the different primary color images arises. If the severalelectron guns are parallel and common deflecting fields are employed,the corresponding three scanning rasters will be displaced at theviewing screen unless additional means are employed to produceregistration. One expedient which has been employed is to produceso-called convergence fields by an electrostatic or electromagnetic lenssystem so that corresponding points in the three-color images willcoincide on the viewing screen. In general the amount of convergencerequired varies with the position of the picture points and dynamicconvergence signals are required which can be quite complex. Any errorsin convergence can. produce serious misregistration in the colorpicture. In the single-gun versions wherein a deflecting field isapplied to cause the electron beam to impinge on the viewing screensuccessively from diiferent directions, a similar problem ofregistration arises.

Several different color scanning methods have been proposed in the past,and can be employed with one or more of the tubes described above. Thescanning methods can be divided broadly into simultaneous andvsequential categories, depending upon whether the several primarycolors are reproduced simultaneously or suc- 2 essively. The sequentialcategory can be sub-divided into field, line, and dot sequentiaiarrangements, wherein the several primary colors alternate at field,line or dot frequency, respectively. Other specific scanning methodshave been proposed but the above suffices for explaining the-presentinvention.

In simultaneous scanning systems several electron beams corresponding innumber to the primary colors coexist and are simultaneously deflectedover the reproducing screen inv horizontal and vertical directions bythe same scanning fields. Consequently any convergent signals employedto effect registration are applied simultaneously to all three beams.Since the three beams will in general not occupy the same region. in theconvergence field, it is difiicult to obtain precise registration.

In the sequential systems the scanning beams corresponding to diiferentcolors exist sequentially, and consequently the scanning fields affectonly one scanning beam at. a time. It is thus possible to use somewhatdifferent convergence signals for scanning, beams corre sponding, todifferent colors in order to obtain more perfoot registration, althoughthe necessary circuitry may become quite complicated.

In accordance with the present invention the relative phase of the videosignal waves and corresponding deflection waves are changed from colorto color in order to effect the desired registration. In the case ofsimultaneous systems where common deflecting fields ars employed for theseveral beams, the video signal Waves corresponding to the diflerentcolors are delayed by different amounts. In the case of sequentialsystems the change in relative phase can be produced in the same manner,that is by appropriate delay of the video signals. However, in the caseof line and field sequential systems, change in phase can also beproduced by delaying the deflection waves rather than the video waves.

Usually common deflection means such as a single set of deflecting coilsor plates are employed. for the several beams even in sequential typesystems. Inasmuch asthe several beams are not likely to traverse exactlythe same portions of the deflecting fields during their deflection, thescanning rasters may not be identical, In accordance with the presentinvention such distortion can often be reduced or eliminated by the useof variable delay to produce a variable change in phase during thereproduction of one or more primary colors.

The invention will be more fully understood by a consideration of thefollowing detailed description thereof taken in conjunction withdrawings in which:

Fig. 1 illustrates a three-gun mask-type tri-color tube with which theinvention may be employed;

Fig. 1(a) is a detail illustrating a single gun with deflection toproduce three axially-separated beams;

Fig. 1(b) is a block diagram of a general receiver arrangement for thetube of Fig. 1; i

Fig. 2 is a detail further explaining the construction of the tubes ofFigs. 1 and 1(a);

Fig. 3 illustrates details of a tube in are triangularly arranged Fig. 4illustrates the use of delay to register images whose centers ofdeflection are on a line;

Fig. 5 is an explanatory diagram similar to Fig. 4 but in which thecenters of deflection are triangularly arranged; 1

Fig. 6 is a diagram showing how the relative phase may be changed bydelaying either video or deflection waves;

Fig. 7 illustrates a simple circuit for producing diflierent delays of avideo signal;

Fig. 8 is a circuit for the delay of synchronizing sigwhich the guns 0nals;

Fig. 8(a) illustrates gating Waveforms used in Fig. 8;

placed positions of beam 23 thus correspond to the J) observed in tubessuch as shown in Fig. 1 and the correction thereof;

Fig. is a circuit diagram for producing variable delay to reduce thetype of distortion shown in Fig. 9(a);

Figs. 10(a), (b) and (c) are details showing certain waveforms of thecircuit of Fig. 10; and

Fig. 11 is a block diagram illustrating a general arrangement fordelaying deflection waves.

Referring now to Fig. 1 a tri-color cathode-ray tube is shown comprisingan evacuated envelope 12, of glass or metal, with an appropriate base13. In the neck of the tube are mounted three electron guns 14G, 14B and14R which generate electron beams for reproducing different colors, hereassumed to be green, blue and red aspects of the picture, respectively.At the other end of the tube is a reproducing screen 15 of thefluorescent type with an interposed apertured mask 16. Reproducingscreen 15 contains a large number of minute areas in different colorphosphors in a desired geometric pattern. The apertures in mask 16 arearranged in a cooperating geometric pattern.

Vertical deflecting coils 17 are arranged about the neck of the tube,along with horizontal deflecting coils 18. The cathode-ray beam 19issuing from gun 14B is deflected by the deflecting coils about a centerof deflection designated 21B. Similarly, cathode-ray beams issuing fromguns 14G and 14R are deflected about centers of deflection 21G and 21R.It is of course understood that the actual deflection takes place thruan are rather than at a single point, but the idealized point conceptsuffices for understanding the present invention.

Referring to Fig. 1(a), a single electron gun 22 is illustrated whichreplaces the three electron guns of Fig. l and would ordinarily belocated on the axis of the tube. By suitable deflecting coils or plates,the cathode-ray beam 23 is caused to assume in succession the threepositions designated 24G, 24B and 24R. The successive disseparatelygenerated beams of the tube shown in Fig. 1. In the discussionhereinafter, and in the claims, it will be understood that the termcathode-ray beams refers not only to separately generated beams such asillustrated in Fig. 1, but also to the displaced beams of Fig. 1(a),even though the latter originate from a single gun. It will beunderstood that the three beams MIG-24R of Fig. 1(a) may be deflectedabout spaced centers of deflection such as shown at 21G-2IR of Fig. 1.

Fig. 1(b) shows the tube of Fig. 1 in a typical receiver arrangement.Here the composite television signal including color video signals withassociated line and field synchronizing signals is picked up by antenna1 and fed to receiver circuits 2 which may include, for example, R.-F.,converter, I.-F. and detector stages. color video signals are amplifiedin video channel 3 and the difierent color signals fed to the respectiveelectron guns 14G-14R to control the modulation of the elec' tron beams.The video signals ordinarily are fed to either the cathodes or controlgrids of the electron guns.

The composite signal is also commonly fed to a deflection channel 4wherein the synchronizing signals are separated from the video andemployed to synchronize line and field sawtooth deflection wavegenerators whose outputs are supplied to deflection coils 18 and 17respec- The Y tively. Ordinarily the line and field synchronizing pulsesare separated and fed to separate line and field deflection. wavegenerating channels which are here included within the broad phrasedeflection channel.

The composite video signal may also include distinctive colorsynchronizing signals associated with video signals of one color whichare utilized to insure that a given color signal will be reproduced inthat color.

Details of the utilization of the several synchronizing signals dependon the particular application and are well known in the art. Hencefurther detail is WIIEWSSQIY here.

Referring now to Fig. 2, points 216, 21B and 21R illustrate thehorizontally aligned centers of deflection of the three cathode-raybeams produced as described in connection with either Fig. 1 or Fig.1(a). The apertured mask and fluorescent screen are shown as fragmentsrotated about horizontal axes into the plane of the paper forconvenience of illustration. The apertured mask 16 is here shown as amask 16 having elementary vertical slots 25 which are vertically andhorizontally aligned. The cathode-ray beams are shown as passing throughone slot 25 and impinging on a fluorescent screen 15 composed of narrowvertical strips of green, blue and red phosphors alternating insequence. In general the width of the strips will be less than thediameter of the scanning beam and the actual dimension will depend uponthe amount of detail desired and the diameter of the screen.

Referring now to Fig. 3, an alternative arrangement of the tube of Fig.1 is depicted in which the three guns 14G, 14B and 14R are arranged atthe corners of a triangle, the guns being parallel to each other. Anendon view of the guns is shown in Fig. 3(a). In this case the aperturedmask 16" has apertures 26 (Fig. 3(b)) arranged so that a trefoil ofphosphor dots can be arranged behind each aperture. The phosphor dotsare shown in Fig. 3(c) at 27G, 27B, and 27R, respectively. Each trefoilis located behind one of the apertures 26 of Fig. 3(b) and the locationof apertures 26 are shown in dotted lines in Fig. 3 (c).

It will be understood that the geometrical arrangement of apertures andphosphors in Figs. 13 is subject to wide variation, and the order of thecolors can be selected as desired. The specific arrangements here shownare illustrative only. Generally speaking, the geometry of the systemsare such that electrons appearing to pass through one center (such as21R) strike only the red phosphor elements, those appearing to passthrough another center (such as 213) strike only the blue phosphorelements, and those appearing to pass through a third center (such as216) strike only the green phosphor elements.

Referring now to Fig. 4, the manner in which delay may be employed toregister the color images of tubes such as shown in Figs. 1, 1(a) and 2is illustrated. Points 21G, 21B, and 21R again represent the centers ofdeflection of the electron beams corresponding to diflerent colors, andare spaced apart in the line-deflection direction. With the three gunsof Fig. 1 these electron beams may exist simultaneously or sequentiallydepending upon the scanning method employed. With the arrangement ofFig. 1(a), they will exist sequentially.

If the cathode-ray beams are acted upon by the same deflecting fieldseither simultaneously or successively, the lateral displacement of thecenters of deflection will re sult in three horizontally-displacedscanning rasters or areas being formed at the fluorescent screen asshown at 31R, 31B and 316 of Fig. 4(b). These rasters will besubstantially overlapping and will occupy approximately coextensiveareas except for lack of registry. In the ideal case, the three scanningrasters will be identical except for the lateral displacement. Thecorresponding primary color images will also be laterally displaced asshown by the images of a circle denoted 32R, 32B and 32G.

Fig. 4(c) illustrates obtaining registration by delay of the video waveswith respect to the corresponding horizontal deflection waves. Sinceonly relative delay is important, it is assumed that the green videosignal is reproduced as in the case of Fig. 4(b). Consequently thecircle 33 representing the reproduced circle in all three colorsoccupies the same position with respect to scanning raster 316 that itdid in Fig. 4(b). However, the video signal corresponding to blue hasbeen delayed with respect to its scanning raster 3113 by a fraction of.a line period to superpose the blue image on the green image. The actualamount of delay will of course depend upon'the initial amount ofmisregistration, the size of the picture and the speed ofhorizontalsweep. The video signal corresponding to red is delayed by approximatelytwice the amount of the blue signal so as to superpose the red imagelikewise on the green image, so that all three colors then occupy theposition shown by circle 33.

The delay of the video illustrated in Fig. 4(c) is applicable to anytype of scanning system, whether simul taneous or sequential. In thecase of field and line sequential systems it is also possible to delaythe deflection waves rather than the video waves. Referring to Fig.4(d), the relative phase of'the red video signal and its correspondingdeflection Wave are the same as in Fig. 4(b), so that circle 33'occupies the same relative position with respect to its scanning raster31R. However, scanning raster 31B is delayed with respect to the videoby a small fraction of a line period to cause the blue image to coincidewith the red image. The actual position of the scanning raster 31B onthe face ofthe cathoderay tube will remain the same as in Fig. 4(b)since the magnitude of the deflection current or voltage is'assumed tobe the same. However, since the deflection wave has been delayed,thereby changing the relative phase of the video and deflection waves,the blue video signal will occur earlier in the deflection cycle andhence the blue image will be displaced to the left (deflection beingassumed to proceed from left to right as in conventional practice). Thedeflection wave for the green signal is delayed by approximately twicethe amount for the blue so that the green image will also coincide withcircle 33'.

The time sequence of the video and deflection signals described inconnection with Fig. 4 will be more clearly understood by reference toFig. 6. Here horizontal (line) sawtooth deflection waves 34R, 34B, 34Gare shown in Fig. 6(a) for red, blue and green signals. Likewise, red,blue and green video signals 35R, 35B, 35G for a given line are shown inFig. 6(b).

Fig. 6(0) corresponds to Fig. 4(a), both illustrating effectingregistration by delay of the video. In this figure the green videosignal 35G has the same phase relative to the deflection wave 346 thatit did before. However, the blue video signal 35B has been delayed sothat it occurs later relative to scanning wave 34B. Consequently thecorresponding line will be shifted to the right in the picture, as wasexplained in connection with Fig. 4(c). The red video signal wave 35R isdelayed by approximately twice the delay of the blue signal, and occursstill later in the course of its deflection wave 34R. Consequently thecorresponding red line is shifted still farther to the right in thepicture as was explained in Fig. 4(c).

Other lines of the pictures Will be shifted in the manner just describedso that the entire area of the red and blue images are shifted intocoincidence or registry with the green image.

For field and line sequential systems the deflection and video Waveswill occur successively. For dot sequential systems the video waves35R-35G will be interlaced and deflection waves Mill-34G will be one andthe same wave. For simultaneous systems the deflection waves 342-346will also be one and the same wave. Thus it is apparent that the delayof the video can be employed to obtain registration with any of thesesystems.

Fig. 6(d) illustrates delay of the deflection waves, and corresponds toFig. 4(d). Here deflection wave 34R remains unchanged, and occurs in thesame relative phase with respect to the video signal 35R that it didoriginally. Deflection wave 343 is delayed with respect to its originalposition 34B so that the video signal 35B occurs earlier on the trace.Deflection wave 34G is still further delayed with respect to itsoriginal position 34G, so that the corresponding video signal 35G occursstill earlier on the trace. Thus the blue aspect of the image isdisplaced toward the left of the picture by a given amount, and thegreen aspect of the image displaced to the left by approximately twicethat amount, so that all three color aspects are superposed as shown at33' in Fig. 4(a').

It will be observed from Fig 6 that the change in relative phase of thevideo signal waves and the corresponding deflection waves may beaccomplished by delaying either the video signal or the deflection wave,the choice depending upon the particular application.

Referring now to Fig. 5, there is depicted the use of delay to registerimages produced by triangularly arranged electron beams, produced eitherby three separate guns or by one gun with successive deflection tothreedifferent triangularly arranged positions. In the absence of convergencesignals the scanning rasters on the face of the tube will occupy thepositionsshown inFig. 5 (b) at 31R, 31B and 316. Respective coloraspects of a circular image will occupy the position shown at 32R, 32Band 32G. Since these images also bear a triangular relationship, it isnecessary to alter the location of one or more of the images bothhorizontally and vertically in order to obtain registration. Inaccordance with the present invention the relative phase of the videoand deflection waves is altered by fractions of a line so as to alignthe three color images horizontally, and delay corresponding to severallines is employed to align the images in the vertical direction.

Fig. 5(c) represents delay of the video signal. Scanning is assumed toproceed from top to bottom and from left to right in the conventionalmanner. Since circle 326' in Fig. 5(b) is farthest to the right (thatis, farthest in the direction of horizontal line scanning), the videosignals corresponding to the blue and redaspects are delayed byintervals corresponding to small fractions of the line period so as toalign them in the horizontal direction. These delays will bring thecenters of the red and blue circles to the vertical line 36. The red andgreen video signals are also delayed by the necessary number of lines (afraction of the vertical or field scanning period) to displace theircenters in a vertical direction into coincidence with that of the bluecircle. The result is shown by the circle 37.

If the displacement of the unregistered images were inverted from thatshown in Fig. 5 (b), with circle 32B at the top of the triangle, thesame horizontal delays would be employed but in this case only the bluesignal would be delayed by the necessary number of line periods to bringit into coincidence with the others. The numerical values of the delayswill depend upon the factors discussed in connection with Fig. 4.

Fig. 5 (d) illustrates obtaining registration of the images of Fig. 5(b)by the use of delay in the deflection circuits. Here the deflection wavecorresponding to the blue aspect will be delayed by a fraction of a lineperiod to bring blue image into horizontal alignment with the red image,so that the centers will lie on line 38. The deflection wavecorresponding to the green image will be delayed approximately twice asmuch so that its center also will lie on line 38. The deflection wavefor the blue signal is additionally delayed by a number of line periodsso that all three images are superposed as shown at 37 in Fig. 5(d).

it will be observed that although the use of delay in accordance withthe present invention registers the reproduced primary color images, thecorresponding scanning rasters do not coincide. Suitable masking may beemployed so that the outer portions of the scanning rasters areconcealed from view. It will of course be understood that thedisplacements of the scanning rasters shown in Figs. 4 and 5 have beenexaggerated for clarity of illustration and that only a small percentageof the. overall picture area need be masked.

The displacement of the scanning rasters may be re.- duced by an initialinward pointing (toward the center line of the tube) of the cathode-raybeams. For example,

with three guns their axes may converge somewhat in- .stead of beingparallel. This also reduces the delay time required for registration.However, the inward pointing ing for the horizontal blanking interval,the delays required calculate to be approximately 0.0131-1 and 0.027H,where H is the horizontal line period. With the presently establishedFCC color standards of 405 lines and 144 fields per seconddouble-interlaced, H is approximately 34.3 microseconds and the requireddelays are approximately 0.46 and 0.92 microsecond. For differentseparations of color centers, different size screens, and differentline. periods, appropriate calculations can readily be made.

In the case of vertical displacements, assume that the .vertical spacingof adjacent color centers is 0.2 inch and the other conditions as above.This spacing corresponds to approximately four lines of a single field,with double interlacing, and the delay is accordingly 4H.

Referring now to Fig. 7, a simple circuit is shown for delaying thevideo signals in tubes of the type employing three separate electronguns. Here 41 represents the .video output tube of the televisionreceiver and 42 represents the DC. reinserter.

These circuits may be conventional and need not be shown in detail. Inthe output of tube 41 is disposed a delay network comprising sections42, 43, and 44 with a suitable terminating impedance 45. The delaynetwork is shown as a simple L-C delay line but of course may beelaborated if desired. The design and construction of delay lines iswell known in the art and need not be described in detail.

The circuit of Fig. 7 may be used to produce registration as explainedin connection with Fig. 4(c). As there explained, the green signal isundelayed and corresponds to the output connection 46 from the inputpoint of the delay line. The blue signal is delayed by a given amountand may be obtained through output connection 47 from an intermediatepoint of the delay line, it being understood that the delay produced innetwork 42 is selected to cause the blue image to register with thegreen image. The red signal is delayed still more and may be obtainedfrom output connection 48. The output signals at terminals 4648 may beapplied to the grids or cathodes of the respective electron guns inconventional manner.

The circuit of Fig. 7 may also be designed to produce the delaysdescribed in connection with Fig. 5(a). In this event however, since allsignals are delayed to some extent, an additional delay section will beinterposed between output tube 41 and delay section 42. The smallestdelay is that of the blue signal and corresponds to a small fraction ofa line AH so that the blue output signal would then be taken fromterminal 46. The green signal is delayed by a predetermined number oflines so that filter section 42 would be designed to delay the signal bythe given number of lines minus the delay of the previous filter sectionand would be taken from output terminal 47. The red signal is delayed bythe same number of lines plus twice AH. Thus section 43 of the delayline will be designed to produce 2AH delay and the green signal would betaken from terminal 48.

It will be understood that the circuit shown in Fig. 7 is adapted foruse with sequential scanning systems wherein separate gating signals areapplied to the guns of the cathode-ray tube to turn on the beams insequence. Thus the video channel provides three signal paths to the tubewhich are gated to operate successively for different colors. In thecase of simultaneous systems the video signals corresponding todifierent colors are commonly separated in the receiver and fed torespective electron guns through separate channels. In this case a delaycircuit may be interposed in each channel to produce the required delayas explained in connection with Figs. 4-6.

The delay of the deflection waves can be produced by delaying thesynchronizing signals which initiate or control the deflections, or byintroducing suitable control signals elsewhere in the deflectionchannels. Fig. 8 illustrates a suitable circuit for delayingsynchronizing signals in a field sequential system. It will beparticularly described to effect registration in the manner shown inFig. 4(d).

Gate generator 51 is'synchronized with the field signals and adapted togenerate gates of the type shown in Fig. 8(a). Suitable generators areknown in the art and need not be described in detail. A red gate signalhas passing pulses 52R occurring with each red field scansion, andcut-oil? portions 53R therebetween. Similar passing and cut-off pulsesare generated for the blue and green gates. Horizontal synchronizingpulses are applied at 54 to a delay line generally designated as 55.Gated electron tubes 56R, 56B and 566 have their respective controlgrids connected to spaced points on the delay line. The gating signalsfrom generator 51 are also applied to these tubes. Any suitableamplifier tubes may be employed and the gating signals may be appliedthereto in any convenient manner known in the art. It is usuallydesirable to apply the gating signals to other than the control gridsand in the case of triodes they may conveniently be applied to thecathodes. If pentodes are used the gating signals may be applied to thecathodes, screen grids or suppressor grids. The polarity of the gatingsignals depend upon the electrodes to which they are applied as will beunderstood.

As indicated in the discussion of Fig. 4(d), the deflection Wavescorresponding to the red signal are undelayed. Accordingly the controlgrid of tube 56R is connected to the input of the delay line andhorizontal synchronizing pulses appearing in the common output line 57will be u ndelayed. During the red field scansion tube 56R is on, andtubes 56B and 566 are off. During the blue field scansion, tube 56B ison and the other tubes ofi. Consequently the horizontal synchronizingsignals corresponding to the blue scansions will be delayed by the firstportion of delay line 55 by the amount necessary to register the blueimage with the red image. As explained before this is a small fractionof a line period in the embodiment shown in Fig. 4(d). During the greenfield scansion, tube 566 is on and the others 0E, so that the horizontalsynchronizing signals corresponding to the green scansion are delayed byboth sections of delay line 55. Variable taps on the delay line may beemployed for precise adjustment of registration if desired. The outputfrom line 57 is fed to the line deflection wave generator to control thesynchronization thereof.

The arrangement of Fig. 8 may readily be adapted to scanning methods ofthe line sequential type by gating the tubes 56R-56G at line frequencyrather than at field frequency.

In the arrangement depicted in Fig. 5 (d), delay of the deflection wavesin both horizontal and vertical channels is required. In this event, thecircuit of Fig. 8 may be employed to delay the horizontal synchronizingsignals in the manner just described. A similar circuit may be arrangedin the vertical synchronizing channel to delay the vertical signals bythe necessary amounts.

If desired, instead of employing delay lines, other devices such asmultivibrators may be used to produce delayed synchronizing pulses. Thismay be particularly advantageous where delay of the verticalsynchronizing signals is required.

It is also possible to use the circuit of Fig. 8 to delay the videosignal by the required amounts, the video being supplied to input 54.Such an arrangement is advantageous in a sequential system employing asingle gun splitter or polarity-inverter.

. 9 tricolor tube, since gating is associated with the delay circuit andthe common output lead 57 can be connected to the single electron gun toprovide sequential video signals with each color properly delayed. For athree-gun tube, tubes 56R56G can be provided with separate outputcircuits leading to respective guns of the tricolor tube. In such casethe gating in the delay circuit insures supplying each gun with theproper color video signal without gating at the guns themselves. Ineither of these cases it will be apparent that three signal paths areprovided in the video channel which are gated to operate successivelyfor video signals of different color respectively.

With spaced centers of deflection of the electron beams in a singlecathode-ray tube, and common focusing and deflection coils orelectrodes, the scanning rasters corresponding to the several centers ofdeflection may not be exactly the same. With the centers of deflectionarranged along a single line, as described in connection with Figs. 1and 1(a), the scanning raster corresponding to the middle center ofdeflection can be made approximately rectangular. This has been assumedto be the blue scanning raster and is shown at 61B in Fig. 9(a). Thesides of the other two scanning rasters are often distorted in themanner shown by the scanning rasters 616 and 61R. It will be noted thatthe distortion of the green raster is the reverse of that of the redraster since the two guns are on opposite sides of the middle gun.

The picture of a square object will yield color images 62R, 62B and 62Gwherein images 62R and 628 have the same type of distortion as that ofthe scanning rasters, in addition to the misregistration previouslydiscussed.

Considering the red image 62R, if the upper and lower lines are moved tothe left with respect to the middle line of the image, the distortioncan be corrected. This can be accomplished by delaying the reddeflection waves for the top and bottom of the picture more than for thecenter of the picture. This will cause top and bottom lines to bereproduced earlier in the respective horizontal deflection cycles andhence will move them to the left of the picture. The result will be astraightening of the lateral sides of the red image as shown at 62R inFig. 9(b). Similarly, the sides of the green image 62G can bestraightened by delaying the deflection waves for the middle of thepicture more than for the top and bottom of the picture. The result isshown at 626'. Then the images can be registered by the use of delay inthe manner described in connection with Fig. 4(d).

In the case most often met with in practice, the distortion of the sidesof the scanning pattern and of reproduced images is generally parabolicin shape. Consequently a variable delay of the red and greensynchronizing pulses which follows the parabolic law will suifice. Inthe usual television receiver employing a self-biased verticaldeflection output tube, a wave exists at the oathode which is' roughlyparabolic in shape. This has been found to be quite satisfactory tocorrect the type of distortion illustrated in Fig. 9. In case othertypes of distortion are present, suitable waves may be found in thetelevision receiver or may be specially generated for the purposes ofcorrection.

Referring now to Fig. 10, a correcting waveform 65, here assumed to beparabolic, is applied at 66 to a gain control 67. This wave is amplifiedby tubes 68 and 69 Whose circuit connections may follow conventionalpractice and need not be described in detail. The parabolic waveform isdepicted at several points in the circuit to indicate polarity. Tube 71is supplied with the amplified parabolic wave and is connected as aconventional phase- The parabolic wave taken from the cathode throughlead 72 has the original polarity as shown at 65'. The wave taken fromthe anode through lead 73 is of similar shape but inverted as shown at655.

Control tubes 81R, 81B and 816 are supplied. with positive grid biasfrom B+ through voltage dividers comprising resistors 83R, 84R, 83B,84B, 836, 84G, respectively. Series resistors 85R, 856 are connected inthe grid circuits of tubes 81R and 81G to permit the application of theparabolic control signals to their control grids through couplingcapacitors 86R and 86G to which leads 73 and 72 are respectivelyconnected. The anodes are connected to a common B+ line 82. No seriesgrid resistor need be provided for tube 81B since its potential is notvaried in the specific embodiment illustrated;

Output voltages are taken from the cathode circuits of respective tubesacross cathode resistors 87R, 87B and 87G, respectively. Tubes SIR-81Gthus function as cathode followers and, since the respective controlgrids are positively biased, the cathode potentials are positive toground and yield output signals having a positiveD.-C. component. Theseoutput signals are connected to the screen grids of pentode tubes 92R,92B and 926 through respective leads 83R, 88B and 886. The latter tubesare gated in sequence by suitable negative gating signals 93R, 93B and93G applied to the suppressor grids thereof. The cathodes are groundedas shown, and the anodes connected to a common output circuit 94 havinga common anode load 90 leading to B+.

Horizontal synchronizing signals of negative polarity are supplied tothe control grid of tube 92R through a coupling capacitor 9 5 andresistor 96. The signals are likewise applied to the control grid oftube 92B through an integrating circuit comprising resistor WB, variabieresistor 93B and capacitor 993. The signals are applied to the controlgrid of tube 926 through a similar integrating circuit comprisingelements 97G, 98G and 99G.

Overall operation of the circuit of Fig. 10 will now be described.

The parabolic wave 65" of positive polarity is applied to the grid oftube 81R and a wave of similar polarity (with a positive D.-C.component) is supplied from the cathode of that tube to the screen gridof tube 92R. Hence, the amplification of tube 92R at the middle of thevertical sweep is greater than that at the beginning and end of thevertical sweep. In consequence the input horizontal synchronizing pulsesfor the red field scansion are amplified to a greater extent for themiddle lines than for the top and bottom lines.

Fig. 10(a) shows at 101 an applied horizontal synchronizing pulse on anenlarged and somewhat exaggerated scale. Due to bandwidth limitations inconventional television receivers these pulses are not strictlyrectangular but have curved leading and trailing edges. If the slope ofthe leading edge is not suflicient for the purpose, it can readily bemade so by an integrating circuit as will be described in connectionwith tubes 92B and 92G.

Fig. 10(1)) represents the output synchronizing pulse 101 of tube 92Runder conditions of relatively low amplification such as occurs for thetop and bottom lines of the picture. The synchronization of thehorizontal deflection wave generator ordinarily depends upon apredetermined difference in potential Vs, such as illustrated by theline 102. The triggering of a blocking oscillator by a synchronizingsignal applied to its grid circuit is an example and will here beassumed.

Fig. 10(c) illustrates an output pulse of tube 92R with greateramplification due to a higher screen voltage such as would occur duringthe middle lines of the picture. Line 103 denotes the voltage Vsrequired to synchronize the horizontal oscillator and is the same asinFig. 10( b).

Due to the greater amplification, the time n required for the leadingedge of the pulse to reach the potential Vs in Fig. 10(0) is less thantime is in Fig. 10(1)). Consequently the synchronization of the linedeflection wave generator is delayed for the top and bottom b lines ofthe picture with respect to the middle lines. The delay follows theparabolic law approximately and is in the proper direction "to correctfor the distortion of the red image as illustrated in Figs. 9(a) and9(b).

The invert ed parabolic waveform 65 is supplied through lead 72tocontrol tube 816, and thence to the screen grid of tube 926. Theamplification of tube 926 is thus greater at the top and bottom of thepicture than at the middle. This results in delaying the horizontalsynchronizing pulses for the middle of the picture more than for the topand bottom, which is in the proper direction to correct for thedistortion of the green image as shown in Figs. 9(a) and 9(1)).

The operation of the circuit of Fig. 10 as explained thus far wouldresult in three substantially undistorted overlapping color images asshown in Fig. 9 (b), but the images are still not in registry. Thenecessary delay of the horizontal synchronizing pulses corresponding tothe blue image is accomplished withthe aid of the integrating circuit inthe input to tube 9213. The values of elements 9713-9913 are selected sothat the leading edge of the synchronizing pulse supplied to 923 has agreater rise time than that for tube 92R. This is shown by leading edge104 in Fig. 10(11). An output pulse of similar shape but invertedpolarity will be produced by tube 92B and its leading edge isrepresented at 164 in Fig. 1012. It will be understood that theamplitude of the pulse need not be the same as that appearing in theoutput of tube 92R under minimum amplification conditions, but may beselected as desired.

It will be observed that due to the greater rise time of leading edge104, the time ta taken to reach the synchronizing potential V5 is longerthan tz for the red signal. By appropriate selection of theamplification of tube 923 and adjustment of the grid circuit by variableresistor 983, a delay of the synchronizing pulses for the blue signalsuflicient to register the blue image with the red image may beobtained. Since the blue image was assumed to be initially undistorted,no variable screen voltage need be applied to this stage.

The integrating circuit 97G99G at the input to tube 926 may be selectedto give a still greater rise time in the leading edge of the horizontalsynchronizing pulses applied to that tube, as shown at 105 in Fig.10(a). The corresponding output pulse will have a leading edge such asrepresented at 105 in Fig 10(1)), and the corresponding time for theleading edge to reach the level V5 is it. Accordingly, the synchronizingpulses for the green signal are delayed more than for the blue signalsand brings the green image into registry with the red and blue images.

The correction of distortion in the red image may involve a slight delayof all portions of the red image, the minimum delay at the center of thepicture being represented as n in Fig. 10(c). With suflicientamplification and sufficiently low value of Vs this time interval may bet negligible. If not negligible, it can of course be taken into accountby slightly increasing the delay of the blue and red synchronizingpulses. Furthermore, even though the delay of the green synchronizingpulses is varied from top to bottom of the picture, the average delayproduced by the effect of the input integrating circuit may be adjustedby resistor 98G so that overall superposition is obtained.

Fig. 10 has been specifically described in connection with a fieldsequential scanning procedure. It may however be readily adapted to linesequential systems, as will be understood by those skilled in the art.In this case the tubes 921 -92G will be gated at line frequency ratherthan at field frequency.

The delay of the deflection waves has been described in connection withFigs. 8 and 10 as being obtained by a delay of the synchronizing pulses.In many cases it is possible to apply control voltages elsewhere in thedeflection signal generator so as to change the phase of the deflectionwaves for different color signals, the choice depending upon thejudgment of the designer.

Fig. 11 is a block diagram illustrating the general phase control ofdeflection waves. Here a color gate generator 111 is synchronized withthe color signals and generates red, blue and green gates. In fieldsequential systems the gates may be at field frequency and in linesequential systems at line frequency. These gates are applied to red,blue and green phase control stages 112R, 112B and 112G. These stagesmay be designed in any desired manner to yield output control waveswhich are different for the diiferent color signals. The outputs maythen be combined and fed to a suitable point in the horizontaldeflection wave generator to control the phase of the deflection waveswith respect to the initial horizontal synchronizing signals. Wherevariable delay for a given color image is desired, dynamic control wavesmay be applied through connection 11 i to the phase control tubes112R112B in any suitable manner.

In the foregoing the invention has been described in connection with anumber of specific embodiments. Many elaborations and embodiments may bedevised within the spirit and scope of the invention as will beunderstood by those skilled in the art. Also in a given application onlyportions of the invention may be used and other portions omitted,depending on the particular application.

I claim:

1. In a color television receiver employing a multi-color tube in whicha plurality of cathode-ray beams are deflected at spaced centers ofdeflection by deflection means and impinge on a reproducing screen toyield respective color images, apparatus which comprises a color videosignal channel connected to said tube for modulating said cathode-raybeams with respective color video signal waves representing differentcolors, a deflection channel for generating deflection wavessynchronized with said video waves and connected to said deflectionmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and a phase control circuit associatedwtih one of said channels for changing the phase of waves thereincorresponding to one color with respect to waves corresponding toanother color, whereby the relative phase of video and deflection wavescorresponding to said one color may be changed with respect to similarwaves corresponding to said other color to shift the reproduced imagesof respective color toward registry.

2. In a color television receiver employing a multicolor tube in which aplurality of cathode-ray beams are deflected at spaced centers ofdeflection by deflection means and impinge on a reproducing screen toyield respective color images, apparatus which comprises a color videosignal channel connected to said tube for modulating said cathode-raybeams with respective color video signal waves representing differentcolors, at deflection channel for generating deflection wavessynchronized with said video waves and connected to said deflectionmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and delay circuit means in one of saidchannels for delaying waves therein corresponding to one color withrespect to waves corresponding to another color to thereby shift thereproduced images of respective color toward registry.

3. In a color television receiver employing a multi-color tube in whicha plurality of cathode-ray beams are deflected horizontally andvertically at spaced centers of deflection by common deflection meansand impinge on a reproducing screen to yield respective color images,apparatus for registering said images which comprises a color videosignal channel connected to said tube for modulating saidcathode-ray'beams with respective color video signal waves representingdiflerent primary colors, at deflection channel for generating line andfield deflection waves synchronized with said video waves and connectedto said common deflection means to deflect said beams over approximatelycoextensive scanning areas of said reproducing screen, and delay circuitmeans in one of said channels for delaying waves therein correspondingto one color With respect to similar waves corresponding to an- 13 othercolor by predetermined amounts to shift the reproduced images ofrespective colors toward registry.

4. In a color television receiver employing a multicolor tube in which aplurality of cathode-ray beams are deflected at spaced centers ofdeflection by deflection means and impinge on a reproducing screen toyield respective color images, apparatus which comprises a color videosignal channel connected in said tube for modulating said cathode-raybeams with respective color video signal waves representing diflerentprimary colors, a deflection channel for generating deflection wavessynchronized with said video waves and connected to said deflectionmeans to deflect said beams over substantially overlapping scannin areasof said reproducing screen, and delay circuit means in one of saidchannels for changing the relative phase of video and deflection wavescorresponding to one color with respect to the relative phase of saidwaves corresponding to another color to shift the reproduced images ofrespective colors toward registry.

5. In a color television receiver employing a multi-color tube in whicha plurality of cathode-ray beams are deflected horizontally andvertically at spaced centers of deflection by common deflection meansand impinge on a reproducing screen to yield respective color images,apparatus for registering said images which comprises a. color videosignal channel connected to said tube for modulating said cathode-raybeams with respective color video signal waves representing diflerentprimary colors, a deflection channel for generating line and fielddeflection waves synchronized with said video waves and connected tosaid common deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen, and delay circuitmeans in one of said channels for changing the relative phase of saidvideo and line deflection waves corresponding to one color with respectto the relative phase of said waves corresponding to another color toshift the reproduced lines of respective color images toward horizontalregistry.

6. In a color television receiver for multi-color video signals havingsynchronizing signals associated therewith and employing a multi-colortube in which a plurality of cathode-ray beams are deflected at spacedcenters of deflection by deflection means and impinge on a reproductionscreen to yield respective color images, apparatus which comprises acolor video signal channel connected to said tube for modulating saidcathode-ray beams with respective color video signals of differentcolor, a deflection channel supplied with said synchronizing signals forgenerating deflection waves synchronized with said video signals andconnected to said deflection means to deflect said beams oversubstantially overlapping scanning areas of said reproducing screen, anda delay circuit in one of said channels supplied with signals thereincorresponding to one color to delay said signals with respect to similarsignals corresponding to another color, whereby the relative phase ofvideo signal and deflection waves corresponding to one color may bealtered with respect to another color to shift the reproduced images ofrespective color toward registry.

7. In a color television receiver for multi-color video signals havingsynchronizing signals associated therewith and employing a multi-colortube in which a plurality of cathode-ray beams are deflected at spacedcenters of deflection by line and field deflection means and impinge ona reproduction screen to yield respective color images, apparatus whichcomprises a color video signal channel connected to said tube formodulating said cathode-ray beams with respective color video signalwaves representing diflferent primary colors, a deflection channelsupplied With said synchronizing signals for generating deflection wavessynchronized with said video signals and connected to said deflectionmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and a delay line in one of saidchannels for 14 delaying waves in said channel corresponding to onecolor by a small fraction of a line period with respect to similar wavescorresponding to another color, whereby the relative phase of video anddeflection waves corresponding to said one color may be changed withrespect to similar waves corresponding to said other color to shift thereproduced images of respective color toward registry.

8. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in' which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing diflerent primary colors, 2. deflectionchannel supplied with said synchronizing signals for generatingdeflection Waves synchronized with said video waves and connected tosaid deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen, a delay circuitin one of said channels for delaying waves therein, and gating means forsaid delay circuit synchronized with waves of one color whereby saidwaves are delayed with respect to corresponding waves of another color,whereby the relative phase of video and deflection waves correspondingto said one color may be changed with respect to similar Wavescorresponding to said other color to shift the reproduced images ofrespective color toward registry.

9. In a color television receiver employing a multicolor tube in which aplurality of cathode-ray beams are deflected by common line and fielddeflection means about centers of deflection having spacing therebetweenin line and field scanning directions and impinge on a reproducing,screen to yield respective color images, apparatus which comprises acolor video signal channel connected to said tube for modulating saidcathode-ray beams with respective color video signal waves representingdifferent primary colors, a deflection channel for generating line andfield deflection waves synchronized with said video waves and connectedto said common deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen, delay circuitmeans in one of said channels for changing the relative phase of videoand line deflection waves corresponding to one color by a small fractionof a line period with respect to the relative phase of wavescorresponding to another color to shift the reproduced images ofrespective color toward horizontal registry, and delay circuit means inone of said channels for changing the relative phase or" video and fielddeflection waves corresponding to one color by a number of line periodswith respect to Waves corresponding to another color to shift thereproduced images of respective color toward vertical registry.

10. In a color television receiver employing a multicolor tube in whicha plurality of cathode-ray beams are deflected at spaced centers ofdeflection by deflection means and impinge on a reproducing screen toyield respective color images, apparatus which comprises a color videosignal channel connected to said tube for modulating said cathode-raybeams with respective color video signal waves representing differentcolors, a deflection channel for generating deflection wavessynchronized with said video waves and connected to said deflectionmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and a de lay circuit associated withsaid video channel for delaying video waves therein corresponding to onecolor with respect to video waves corresponding to another color tothereby shift the reproduced images of respective colors towardregistry.

11. In a color television receiver employing a multicolor tube in whicha plurality of cathode-ray beams are deflected at spaced centers ofdeflection by deflection means and impinge on a reproducing screen toyield respective color images, apparatus which comprises a color videosignal channel having a plurality of output circuits connected to saidtube for modulating said plurality of cathode-ray beams with videosignal waves of respectively different color, a deflection channel forgenerating deflection waves synchronized with said video waves andconnected to said deflection means to deflect said beams oversubstantially overlapping scanning areas of said reproducing screen, anda delay circuit in at least one of said output circuits to delay thecorresponding color video signal therein by a predetermined amount withrespect to another color video signal to thereby shift the reproducedimages of respective color toward registry.

12. In a color television receiver employing a multicolor tube in whicha plurality of cathode-ray beams are deflected horizontally andvertically at spaced centers of deflection by common line and fielddeflection means and impinge on a reproducing screen to yield respectivecolor images, apparatus for registering said images which comprises acolor video signal channel connected to said tube for modulating saidcathode-ray beams with respective color video signal waves representingdifferent colors, a deflection channel for generating line and fielddeflection waves synchronized with said video waves and connected tosaid common deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen which arerelatively displaced in the line-scanning direction, and a delay circuitin the path of the video signal of one color predetermined to delay saidsignal by a small fraction of a line period with respect to the videosignal of another color to thereby shift the reproduced images ofrespective colors toward registry.

13. In a color television receiver employing a multicolor tube in whicha plurality of cathode-ray beams are deflected horizontally andvertically at spaced centers of deflection by common line and fielddeflection means and impinge on a reproducing screen to yield respectivecolor images, apparatus for registering said images which comprises acolor video signal channel connected to said tube for modulating saidcathode-ray beams with respective color video signal waves representingdifferent primary colors, a deflection channel for generating line andfield deflection waves synchronized with said video waves and connectedto said common deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen which arerelatively displaced in the line-scanning direction, and a delay circuitin the path of the video signal of one color predetermined to change therelative phase of said video signal and the corresponding linedeflection wave by a small fraction of a line period with respect to therelative phase of video and line deflection waves corresponding toanother color to thereby shift the reproduced images of respective colortoward registry.

14. In a color television receiver for sequential militicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing different primary colors, said video channelhaving a plurality of signal paths gated to operate successively forvideo signals of different color respectively, a deflection channelsupplied with said synchronizing signals for generating deflection wavessynchronized with said video waves and connected to said deflectingmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and a delay circuit in one of saidsignal paths predetermined to delay video signals of corresponding colorwith respect to video sigid nals of different color in another of saidsignal paths to thereby shift the reproduced images of respective colortoward registry.

15. In a color television receiver for tri-color sequential videosignals employing a tri-color tube in which three cathode ray beams aredeflected by common line and field deflection means about centers ofdeflection having spacing therebetween in the line-deflection directionand impinge on a reproducing screen to yield respective color images,apparatus for registering said images which comprises a deflectionchannel for generating line and field deflection waves synchronized withsaid video signals and connected to said common deflection means todeflect said beams over substantially overlapping scanning areas of saidreproducing screen which are relatively displaced in the line-scanningdirection, a color video signal channel supplied with said tri-colorvideo signals and having a video delay line associated therewith,connections from different points on said delay line to said tube tomodulate said cathode-ray beams with respective color video signals ofdifferent delay, said connections being predetermined to delay thereproduction of at least two colors by small fractions of a line periodto thereby shift the reproduced images of said two colors intohorizontal registry with the third color image.

16. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing different colors, a deflection channelsupplied with said synchronizing signals for generating deflection wavessynchronized with said video waves and connected to said deflectionmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and delay circuit means associatedwith said deflection channel for delaying deflection waves correspondingto one color with respect to deflection waves corresponding to anothercolor to thereby shift the reproduced images of respective colors towardregistry.

17. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing different colors, a deflection channelsupplied with said synchronizing signals for generating deflection wavessynchronized with said video waves and connected to said deflectionmeans to deflect said beams over substantially overlapping scanningareas of said reproducing screen, and a phase control circuit associatedwith said deflection channel synchronized with said video signals toalter the phase of deflection Waves corresponding to one color withrespect to deflection waves corresponding to another color to therebyshift the reproduced images of respective color toward registry.

18. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing different colors, deflection wave generatingmeans connected to said deflection means to deflect said beams 17 oversubstantially overlapping scanning areas of said reproducing sc'r'een,delay circuit means supplied with said synchronizing signals fordelaying synchronizing signals corresponding to one color with respectto synchronizing signals corresponding to another color, and connectionsfrom said delay circuit means to synchronize said deflection wavegenerating means, whereby the reproduced images of said colors may beshifted toward registry.

19. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respectivecolor videosignal waves representing different primary colors, deflection wavegenerating means connected to said deflection means to deflect saidbeams over substantially overlapping scanning areas of said reproducingscreen, delay circuit means supplied with said synchronizing signals fordelaying the synchronizing signals corresponding to one color relativeto the respective color video signals to change the relative phasethereof with respect to the relative phase of synchronzing and videosignals of another-color, and connections supplying the delayedsynchronizing signals to said'deflection wave generating means tothereby shift the reproduced images of said colors toward registry.

20. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing different primary colors, deflection wavegenerating means connected to said deflection means to deflect saidbeams over substantially overlapping scanning areas of said reproducingscreen, a delay line supplied with said synchronizing signals, andconnections to said deflection wave generating means from differentpoints on said delay line yielding synchronizing signals of diflerentdelay relative to the corresponding color video signals, whereby thereproduced images of said colors may be shifted toward registry.

21. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosignal waves representing different primary colors, deflection wavegenerating means connected to said deflection means to deflect saidbeams over substantially overlapping scanning areas of said reproducingscreen, a delay line supplied with said synchronizing signals, aplurality of gated tubes synchronized with said color video signals andconnected to respectively different points on said delay line to yieldcontrol synchronizing signals whose phase with respective color videosignals is different for different colors, and connections supplyingsaid control synchronizing signals to said deflection wave generatingmeans to control the synchronization thereof and thereby shift thereproduced images of said different colors toward registry.

22. In a color television receiver for sequential multicolor videosignals having line and field synchronizing signals associated therewithand employing a multi-color tube in which a plurality of cathode-raybeams are deiflected by common line and field deflection means aboutrespective centers of deflection having spacing therebetween in theline-deflection direction and impinge on a reproducing screen to yieldrespective color images, apparatus for registering said images whichcomprises a color video signal channel connected to said tube formodulating said cathode-ray beams with respective color video signalsrepresenting different colors, line and field deflection wave generatorsconnected to respective deflection means to deflect said beams oversubstantially overlapping scanning areas of said reproducing screenwhich are relatively displaced in the line-scanning direction, a delayline supplied with said line synchroniz ing signals, a plurality ofgated electronic tubes synchronized with said color video signals havinga common output circuit and respective input circuits connected todifferent points on said delay line to yield output controlsynchronizing signals whose phase with respective color video signals isdifferent for different colors, and a connection from said outputcircuit to said line deflection generator to control synchronizationthereof and thereby shift the reproduced images of said different colorsinto horizontal registry.

23. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at spaced centers of deflection by common deflection means andimpinge on a reproducing screen to yield respective color images,apparatus which comprises a color video signal channel connected to saidtube for modulating said cathode-ray beams with respective color videosig nal waves representing different primary colors, deflection wavegenerating means connected to said common deflection means to deflectsaid beams over substantially overlapping scanning areas of saidreproducing screen, a plurality of electronic tubes supplied withsynchronizing pulses and gated to operate successively during thereproduction of respective successively different colors, connectionssupplying the output synchronizing pulses of said tubes to saiddeflection wave generating means to control the synchronization thereof,and a circuit associated with at least one of said tubes to increase therise time of the output pulses from said tube whereby the correspondingdeflection waves are delayed to shift reproduced images of correspondingcolor toward registry with images of another color.

24. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at centers of deflection having lateral spacing therebetweenby common vertical and horizontal deflection means and impinge on areproducing screen to yield respective color images, apparatus whichcomprises a color video signal channel connected to said tube formodulating said cathode-ray beams in sequence with color video signalwaves of respectively different primary color, vertical and horizontaldeflection channels for generating respective field and line deflectionwaves synchronized by said synchronizing signals and connectedto'respective deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen, the sides of thescanning area corresponding to one color being distorted with respect toanother, a phase control circuit connected in said horizontal deflectionchannel operable to change the phase of deflection waves correspondingto one color relative to the video signal of like color, a source of acontrol wave whose magnitude varies during a fieldscanning period, andconnections supplying said control wave to said phase control circuit tochange the relative phase of the video signal and deflection waves ofone color by an amount varying over a field scansion to thereby at leastpartially correct distortion of images in said distorted scanning area.

25. In a color television receiver for sequential multicolor videosignals having synchronizing signals associated therewith and employinga multi-color tube in which a plurality of cathode-ray beams aredeflected at centers of deflection having lateral spacing therebetweenby common vertical and horizontal deflection means and impinge on areproducing screen to yield respective color images, apparatus whichcomprises a color video signal channel connected to said tube formodulating said cathode-ray beams in sequence with color video signalWaves of respectively different primary color, vertical and horizontaldeflection channels for generating respective field and line deflectionwaves synchronized by said synchronizing signals and connected torespective deflection means to deflect said beams over substantiallyoverlapping scanning areas of said reproducing screen which arerelatively displaced in the line-scanning direction, the sides of thescanning area corresponding to one color being distorted with respect toanother, a phase control circuit connected in said horizontal deflectionchannel operable to change the relative phase of the video sig nal anddeflection waves corresponding to one color with respect to the relativephase of said waves corresponding to another color to horizontallyregister images of the respective colors, a source of a control wavewhose magnitude varies during a field-scanning period, and connectionssupplying said control Wave to said phase control circuit to change therelative phase of the video signal .and deflection waves of one color byan amount varying over a field scansion to thereby atleast partiallycorrect distortion of images in said distorted scanning area.

26. In a color television receiver for sequential multicolor videosignals having line and field synchronizing signals associated therewithand employing a multi-color tube in which a plurality of cathode-raybeams are deflected by common line and field deflection means aboutrespective centers of deflection having spacing therebetween in theline-deflection direction and impinge on a reproducing screen to yieldrespective color images, apparatus for registering said images whichcomprises a color video signal channel connected to said tube formodulating said cathode-ray beams with respective color video signalsrepresenting diflerent colors, line and field deflection wave generatorsconnected to respective deflection means to deflect said beams oversubstantially overlapping scanning areas of said reproducing screenwhich are relatively displaced in the line-scanning direction, the sidesof the scanning area corresponding to one color being distorted withrespect to another, a plurality of electronic tubes supplied with linesynchronizing pulses of diflerent rise times respectively and gated tooperate successively during the reproduction of respective successivelydifl'erent colors, at least one of saidtubes being of variable gain, asource of a control wave whose magnitude varies over a field-scanningperiod and connections supplying said control Wave to 20.. said one tubeto control the gain thereof, and connections supplying the outputs ofsaid tubes to the line. deflection wave generator to thereby delay thedeflection waves corresponding to one color with respect to another andto vary the delay of deflection waves corresponding to one color over afield-scanning period.

27. In a color television receiver for sequential multicolor videosignals having line and field synchronizing signals associated therewithand employing a multi-color tube in which a plurality of cathode-raybeams are deflected by common line and field deflection means aboutrespective centers of deflection having spacing therebetween in theline-deflection direction and impinge on a reproducing screen to yieldrespective color images, apparatus for registering said images whichcomprises a color video signal channel connected to said tube formodulating said cathode-ray beams with respective color video signalsrepresenting different colors, line and field deflection Wave generatorsconnected to respective defiection means to deflect said beams oversubstantially overlapping scanning areas of said reproducing screenwhich are relatively displaced in the line-scanning direction, the sidesof the scanning area corresponding to one color being distortedWith'respect to another, a plurality of electronic tubes havingrespective input circuits supplied with line synchronizing pulses and acommon output circuit connected to said line-deflection wave generatorto control the synchronization thereof, said tubes being gated tooperate successively during the reproduction of successively differentcolors and at least one tube being of variable gain, an integratingcircuit in the input circuit of at least one of said tubes to increasethe rise time of the synchronizing pulses applied thereto and therebydelay the deflection Waves corresponding to at least one color and shiftthe corresponding reproduced color image toward registry with another, asource of a control wave whose magnitude varies over a field-scanningperiod and connections supplying said control wave to said variable gaintube to vary the gain thereof and thereby vary the delay of thedeflection waves corresponding to one color to at least partiallycorrect distortion of images produced by said distorted scanning area.

